PREMIX FUEL NOZZLE INTERNAL FLOW PATH ENHANCEMENT
A nozzle for gas turbine includes a tubular nozzle body; and a plurality of hollow fuel injection pegs extending radially from the tubular nozzle body at a location between forward and aft ends of the tubular nozzle body; wherein each of the plurality of hollow fuel injection pegs has an external tear-drop cross-sectional shape, and a fuel passage in each of the hollow injection pegs has a substantially matching internal tear-drop cross-sectional shape.
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This invention relates to gas turbine combustor technology and more especially to a gas turbine fuel nozzle construction with enhanced internal flow path design.
BACKGROUND OF THE INVENTIONIn a typical “can-annular” type gas turbine combustor arrangement, several combustors are arranged in an annular array about the turbine rotor axis and supply combustion gases to the first stage of the turbine. A compressor pressurizes inlet air which is then turned in direction (or reverse flowed) to the combustor where it is used to cool the hot gas path components and to provide air to the combustion process. Each combustor assembly comprises a generally cylindrical combustor (incorporating a combustor chamber), a fuel injection system, and a transition piece or duct that guides the flow of the hot combustion gas from the combustor to the inlet of the turbine section. Gas turbines of this type typically may include 6, 10, 14 or 18 combustors arranged about the turbine rotor axis.
One specific dry low NOx emission combustion system includes a fuel injection system for each combustor which is comprised of multiple fuel nozzles supported on an end cover that closes the upstream end of the combustor. Each fuel nozzle includes a swirler and a radially oriented peg assembly downstream of the swirler. The swirler and peg assembly may be a one-piece casting or a multi-piece casting or fabricated assembly, and there are typically 8-10 pegs extending radially away from the fuel nozzle body. Each hollow peg has a teardrop outer shape and an internal round bore supplying fuel to multiple holes or orifices by which the fuel is injected into the combustion chamber. The radially outer ends of the pegs are closed by plugs which cover one or more of the orifices, requiring additional drilling through the plugs to re-open the orifices. In addition, the plugs cause an unwanted internal “step” in the flow path. At the same time, and for certain other low NOx combustion systems, higher fuel flows must be accommodated while maintaining a predetermined fuel supply pressure and the same exterior shape and dimensions. Thus, the internal passages must be enhanced to accommodate the higher flows while maintaining the outer geometry substantially unchanged.
BRIEF DESCRIPTION OF THE INVENTIONIn one exemplary but non-limiting embodiment, there is provided a nozzle for gas turbine comprising a tubular nozzle body; and a plurality of hollow fuel injection pegs extending radially from the tubular nozzle body at a location between forward and aft ends of the tubular nozzle body; wherein each of the plurality of hollow fuel injection pegs has an external tear-drop cross-sectional shape, and a fuel passage in each of the hollow injection pegs has a substantially matching internal tear-drop cross-sectional shape.
In another exemplary but non-limiting embodiment, there is provided a nozzle for a gas turbine comprising a tubular nozzle body; and a plurality of hollow fuel injection pegs extending radially from the tubular nozzle body at a location between forward and aft ends of the tubular nozzle body; a plurality of hollow fuel injection pegs extending substantially perpendicularly radially from the tubular nozzle body at a location between the forward and aft ends; and wherein the tubular nozzle body has a base flange attached to a forward end thereof, the base flange formed with an annular array of elongated arcuate fuel inlet slots for supplying fuel to a passage in the tubular nozzle body which connects to the plurality of fuel injection pegs.
In yet another exemplary but non-limiting embodiment, there is provided the nozzle for a gas turbine comprising a tubular body; and a plurality of hollow fuel injection pegs extending radially from the tubular nozzle body at a location between forward aft ends of the tubular nozzle body; wherein each of the plurality of hollow fuel injection pegs has a radially outer end wall, wherein a fuel passage in each of the hollow injection pegs has a substantially smooth surface extending continuously between said tubular nozzle body and the radially outer end wall.
The invention will now be described in greater detail in connection with the drawings identified below.
With reference to
More specifically, each combustor 14 includes a substantially cylindrical combustor casing 18 which is secured to the turbine casing 20 by means of, for example, bolts 22. The forward end of the combustor casing is closed by an end cover assembly 24 which may include conventional supply tubes, manifolds and associated valves (indicated generally at 26), etc. for feeding gas, liquid fuel and air (and water if desired) to the combustion chamber. The end cover assembly 24 receives a plurality (for example, five) of diffusion/premix fuel nozzle assemblies 28 (only one shown for purposes of convenience and clarity) arranged in a circular array about a longitudinal axis of the combustor.
Turning to
With reference now to
With reference also to
In addition, the radial bore in the prior externally tear-drop shaped fuel injector pegs 42 were round, and located in the wider or leading edge of the tear-drop-shaped peg. In the reconfigured peg, the internal radial passage 68 is matched to the external tear-drop shape, thereby increasing the internal volume of the peg and, in effect, creating a plenum for more accurately optimal feeding of the plural injector holes 70 in the peg.
At the same time, enlarging the internal volume of the passage 68 during the blind casting or other fabrication process employed to make the swirler (36, 40, 42), also makes it possible to create an integral tip or end wall 72, thereby eliminating a commonly found step or shoulder 74 in plug (integral or added) 76 utilized to close the remote end of the fuel injection peg 78 (see
The above-described flow enhancements enable the nozzle to handle higher flows with minimum modifications; minimizes unwanted pressure losses; and permits optimization of the fuel injection profile.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims
1. A nozzle for gas turbine comprising:
- a tubular nozzle body; and
- a plurality of hollow fuel injection pegs extending radially from said tubular nozzle body at a location between forward and aft ends of said tubular nozzle body; wherein each of said plurality of hollow fuel injection pegs has an external tear-drop cross-sectional shape, and a fuel passage in each of said hollow injection pegs has a substantially matching internal tear-drop cross-sectional shape.
2. The nozzle of claim 1 wherein said tubular nozzle body has a base flange attached to a forward end thereof, said base flange formed with an annular array of elongated arcuate fuel inlet slots for supplying fuel to a passage in said tubular nozzle body which connects to said plurality of fuel injection pegs.
3. The nozzle of claim 1 wherein radially outer ends of said plurality of fuel injection pegs are each closed by a core cap having an end wall, said internal tear-drop cross-sectional shape extending continuously between said tubular nozzle body and said end wall; and further wherein an internal interface surface between each of said plurality of hollow fuel injection pegs and said tubular nozzle body is rounded.
4. The nozzle of claim 3 wherein said internal interface surface is rounded on a radius of between about 0.06 and 0.19 inches.
5. The nozzle of claim 2 wherein radially outer ends of said plurality of fuel injection pegs are each closed by a cap having an end wall, said internal tear-drop cross-sectional shape extending continuously between said tubular nozzle body and said end wall; and further wherein an internal interface surface between each of said plurality of hollow fuel injection pegs and said tubular nozzle body is rounded.
6. The nozzle of claim 5 wherein said internal interface surface is rounded on a radius of between about 0.06 and 0.19 inches.
7. The nozzle of claim 2 wherein said passage is defined by a radial space between a first radially outer tube of said tubular nozzle body and a second intermediate tube located concentrically within said tubular nozzle body.
8. The nozzle of claim 3 wherein said core cap is integral with said hollow fuel injection peg.
9. A nozzle for a gas turbine comprising a tubular nozzle body; and a plurality of hollow fuel injection pegs extending radially from said tubular nozzle body at a location between forward and aft ends of said tubular nozzle body; and wherein said tubular nozzle body has a base flange attached to a forward end thereof, said base flange formed with an annular array of elongated arcuate fuel inlet slots for supplying fuel to a passage in said tubular nozzle body which connects to said plurality of fuel injection pegs.
10. The nozzle of claim 9 wherein each of said hollow fuel injection pegs has an internal tear-drop cross-sectional shape, and wherein radially outer ends of said plurality of fuel injection pegs are each closed by an end wall, said internal tear-drop cross-sectional shape extending continuously between said tubular nozzle body and said end wall.
11. The nozzle of claim 10 an internal interface surface between each of said plurality of hollow fuel injection pegs and said tubular nozzle body is rounded.
12. The nozzle of claim 11 wherein said internal interface surface is rounded on a radius of between about 0.06 and 0.19 inches.
13. The nozzle of claim 9 wherein said elongated arcuate fuel inlet slots extend at an acute angle relative to said passage.
14. The nozzle of claim 11 wherein said elongated arcuate fuel inlet slots are each formed by plural round holes formed with overlapping diameters.
15. The nozzle for a gas turbine comprising:
- a tubular body; and
- a plurality of hollow fuel injection pegs extending radially from said tubular nozzle body at a location between forward aft ends of said tubular nozzle body; wherein each of said plurality of hollow fuel injection pegs has a radially outer end wall, wherein a fuel passage in each of said hollow injection pegs has a substantially smooth surface extending continuously between said tubular nozzle body and said radially outer end wall.
16. The nozzle of claim 15 wherein said radially outer end wall is integral with said hollow fuel injection peg.
17. The nozzle of claim 15 wherein an internal interface surface between each of said plurality of hollow fuel injection pegs and said tubular nozzle body is rounded on a radius designed to smooth flow of fuel into said plurality of fuel injection pegs.
18. The nozzle of claim 17 wherein said internal interface surface is rounded on a radius of between about 0.06 and 0.19 inches.
19. The nozzle of claim 15 wherein said radially outer end wall is a discrete cap secured to said hollow injection peg.
20. The nozzle of claim 19 wherein said discrete cap is welded or brazed to said hollow fuel injection peg.
Type: Application
Filed: Jan 15, 2010
Publication Date: Jul 21, 2011
Applicant: GENERAL ELECTRIC COMPANY (Schenectady, NY)
Inventors: Mark William PINSON (Greer, SC), Jason Thurman STEWART (Greer, SC), Jagadish Kumar PERINGAT (Greenville, SC), Gregory Earl JENSEN (Greenville, SC), Jason Patrick TUMA (Taylors, SC)
Application Number: 12/688,050
International Classification: F02C 7/22 (20060101);